Copper Etching Composition for Low-Undercut Semiconductor Patterning
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Solution Overview
Problem
Current copper etching compositions in semiconductor manufacturing face issues such as lateral etching, undercut, damage to aluminum electrodes, incomplete etching, and uneven etching due to isotropic chemical reactions, which affect the reliability and precision of chip interconnections.
Innovation Solution
An etching composition comprising an oxidizing agent (1-30 wt%), an inorganic acid (0.5-20 wt%), an organic acid (0-15 wt%), a chelating agent (0.01-15 wt%), and an ionic compound or additional inorganic acid, specifically using hydrogen peroxide, nitric acid, citric acid, and sodium gluconate, to control etching rates and reduce undercut and metal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet etching is used for copper removal, then etching selectivity and low cost are improved, but lateral etching and undercut occur due to isotropic etching
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by using a mixed acid system (sulfuric acid, nitric acid, and acetic acid) with specific concentration ratios, and controls etching temperature (20-40°C) and pH value (1-3) to achieve anisotropic etching characteristics that reduce lateral etching while maintaining etching selectivity
Solution Approach 2:
The patent uses a composite etching solution containing multiple acids (sulfuric acid, nitric acid, acetic acid) and additives (hydrogen peroxide, boric acid) working together to create a synergistic effect that provides both vertical etching capability and protection against lateral etching, achieving improved pattern accuracy while maintaining reliability
2Productivity
If strong oxidizing agents like persulfate are used, then etching rate is improved, but damage to nickel layer increases
Solution Approach 1:
The patent uses a milder oxidizing system based on nitric acid and hydrogen peroxide instead of strong persulfate, controlling the oxidation potential through pH adjustment (1-3) and temperature control (20-40°C) to achieve adequate etching rate while minimizing nickel layer damage
Solution Approach 2:
The patent employs a controlled oxidation system using nitric acid and hydrogen peroxide as oxidizing agents, which provide sufficient oxidation power for copper removal while being less aggressive toward nickel compared to persulfate, achieving balanced etching performance and layer protection
3Object-affected harmful factors
If hydrogen peroxide is used as oxidizing agent, then nickel layer damage is reduced, but appearance quality of circuit deteriorates
Solution Approach 1:
The patent combines hydrogen peroxide with nitric acid, sulfuric acid, and acetic acid in specific proportions to create a composite etching solution that balances the gentle oxidation toward nickel with sufficient etching capability for copper, while the acetic acid component helps improve appearance quality by controlling reaction byproducts
Solution Approach 2:
The patent optimizes the concentration of hydrogen peroxide (0.1-5% of total acid content) and controls pH (1-3) and temperature (20-40°C) to enhance the appearance quality of etched circuits while maintaining protection of the nickel layer, achieving both goals through parameter optimization
4Device complexity
If conventional etching composition is used, then etching process is simple, but bubbles form causing incomplete and uneven etching
Solution Approach 1:
The patent controls the pH value (1-3) and temperature (20-40°C) of the etching solution to optimize the chemical reaction kinetics, preventing bubble formation that causes uneven etching while maintaining a relatively simple process workflow
Solution Approach 2:
The patent introduces boric acid as an intermediary substance in the etching solution that helps stabilize the chemical environment, suppress bubble formation, and improve etching uniformity without significantly complicating the overall process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition effectively alleviates lateral etching, reduces critical dimension loss and undercut, ensures high etching uniformity, and maintains chip reliability with minimal substrate damage, resulting in improved circuit appearance and stable etching properties.
Implementation Method 1
the main oxidizing agent of the etching composition system disclosed in the prior art is peroxide, typically persulfate and hydrogen peroxide
Implementation Method 2
In the etching composition, the bump includes multiple layers of different metal, and the metal of the seed layer is different from the metal layer on the bump
Implementation Method 3
chelating agent (0.01-15 wt %, preferably 0.1-5 wt %, more preferably 0.5-2 wt %), specifically using sodium gluconate
Data Source
AI summary
The present disclosure discloses an etching composition. The etching composition includes: a component A: oxidizing agent 1-30 wt %; a component B: inorganic acid 0.5-20 wt %; a component C: organic acid 0-15 wt %; a component D: chelating agent 0.01-15 wt %; a component E: ionic compound and/or other inorganic acids except the inorganic acid in the component B 0-0.1 wt %; and deionized water.